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Radiator replacement is required to cool the big motor down. I had mine custom made at Precision Race Cars Inc same as Nathan. $250 for the radiator, $50 for the filler cap, $12 shipping. Total $337. I thought it was going to be plug and play . NOT. The outlets were not positioned correctly. The lower outlet touched the A/C compressor.


The top outlet  was good.

The filler cap is a work of art.

Turns out the lower input came too close to the a/c compressor. I had to take it back and have him weld a notch in the elbow.


The miata hold hown clamps had to be enlarged to accommodate the radiator. I found a nice set of PVC boots to give it the shock absorption it needs.

Engine cooling filler cap

Here is a shot of the engine cooler filler cap location. I went to autozone and wondered the heater hose section for various bends and lengths of prebent heater hose to get the water from the engine to the heater routed through the custom radiator filler cap.

Now lets talk cooling. From the jump, with no fans, the car would quickly overheat when not moving. The solution was being worked by David Chow and PRC on his LS6 motor and I benefitted from that work. David went from a single 14" fan, to dual 9" fans in an attempt to improve cooling. I picked up that solution from PRC and installed. PRC made an ultra thin aluminum shroud to fit on the radiator with puller fans. I did have to notch and fit a bit on the fans to get em in. You can see on the 3rd picture I also installed platenuts into the shroud in an effort to make insertion and removal easier. Without these, you have to install the radiator with the fans and fight the thermostat during installation. With the platenuts, I can remove the fans without removing the radiator. The fit is very tight. Results are preliminary but there is improvement in cooling when not in motion. I used 2 relays and the PCM is controlling the, The PCM pulls ground to activate the fans so you have to consider that in your wiring. Also the PCM have some good logic in it to control fans after shut down that is programmable. Picture of that below. All in all, this cooling thing is a bear of a problem. The air has a tough time getting out of the engine bay. And the IAT (Inlet air temp at the MAF) driving down the road is at 190degF. AHHH! Having the intake in the engine bay is not going to work. The capture of gauges below tells the horrible story.


After seeing these figures, more work was required. Both in cooling and IAT.

I fabricated a carbon fiber box to support the filter. Big problem is, getting enough cool air to it. The Intake is ~4" diameter. There is no room for a 4" diameter hose to the front without significant modification. My goal is no louvers, nothing on the outside to give away the V8. With the left headlamp removed, I was able to get a 2" duct by the lamp, cut a 2" hole in the frame assy, and work the scat tube through there to the front. Next, I ran a 3" duct into the wheel well and up through the quarter panel. Temps are now ambient +20. Much better but there is still room for improvement. Next will be ducting the 3" tube down in front of the left front tire area. This will require more work as my computer is there in the way. im gonna settle for this for now.

Next was additional cooling ram air. I took some of my aircraft aluminum .026 sheet and formed a shroud all around the radiator. It fans outward to catch more air. Im hoping to get enough air to eventually run the A/C. I have the condenser in, and compressor in, but no pressure lines yet. This shroud all around the radiator has made temps drop~20 degrees in coolant. Ive been running in stop and go traffic on these hot 95 degree days and the system is keeping up. Will it keep up with the a/c as well. Time will tell.